Initiatives to reduce emissions


Terna focuses its attention on a number of voluntary action programmes aimed at reducing its main sources of greenhouse gas emissions:

  • a programme to limit the proportion of SF6 leaks: Terna has launched several initiatives, such as identifying leaks promptly by means of on-line monitoring systems and seeking technological solutions which increase the sealing of equipment and components;
  • feasibility studies for initiatives on energy conservation in electricity stations;
  • a program for reducing the consumption per km of the corporate vehicle fleet, which entails a reduction of CO2 emissions per km (g/km) based on replacing vehicles with better performing equivalents;
  • a program for the energy efficiency of buildings (offices).

The first two cases are initiatives which can have a significant quantitative effect, but only in the medium/long term. In the third case, the results are already tangible but regard a less significant source of emissions from a quantitative point of view.

Containment of SF6 leakage

Thanks to its chemical and physical properties, which make it an excellent insulator, SF6 (sulphur hexafluoride) gas is used as a means of insulation in certain electrical devices such as switches, current transformers and armoured plants. These enable the construction of electricity stations in smaller spaces with reduced maintenance requirements. Thanks to these properties, Terna expects to use more equipment with SF6 gas insulation, as other transmission operators are also doing abroad.

Some of the gas present in the equipment is dispersed into the atmosphere owing to defective seals, on the occasion of breakdowns and, sometimes, during re-pressurising operations. SF6 is classified as a greenhouse gas: Terna operates in order to keep SF6 leaks under control, to limit and if possible reduce the percentage with respect to total gas used. If leaks in absolute terms may increase owing to the greater use of gas, a reduction in the proportion of leaks could, precisely for this reason, have a significant impact in terms of emissions avoided.

Although the proportion of SF6 leaks has been identified as a significant indicator of its performance in relation to climate change, Terna is still studying the matter to identify a target. There are in fact several elements of uncertainty:

  • the growth of awareness and attention to the subject is reflected in an improvement in measuring leaks, entailing – precisely in the years in which the containment activities began (2009-2010) – worsening performance which was most probably only apparent;
  • the occurrence of breakdowns with significant gas leaks – which are increasingly probable given the growing use of SF6 gas in large station equipment – may considerably alter the trend;
  • while on the one hand the installation of equipment with better sealing performance tends to reduce the proportion of leaks, on the other, as the equipment already installed gets older leaks may increase;
  • Terna already has a low proportion of SF6 leaks compared with other TSOs (see the specific box in this paragraph), so further reductions, which have growing marginal costs, can only be limited and with a high probability of being offset by the adverse factors already mentioned, of potentially greater impact.

Net of exceptional breakdowns and of any effect deriving from the ageing of equipment in operation, it is estimated that the installation of new devices with better seals (such as highly reliable transformers), which began in 2009 and continued in the years 2010-2012, could lead to a reduction in the proportion of leaks estimable at 0.1% over five years from the start of the installation campaign, provided that the new equipment is actually available. On the basis of this estimate, and again excluding the factors mentioned, it is expected that by the end of 2014 the proportion of leaks will converge towards figures fluctuating around 0.6%, considering that the average proportion in the period 2005-2009 was 0.7%. 



(*) leaks excluding an exceptional event (1.07% including such an event).

In 2012 the proportion of leaks was 0.59%, down compared with the two previous years (2011: 0.60; 2010: 0.73%). As explained above, the information available does not enable us to interpret these results with certainty as a convergence towards the target.

In 2012 application of the SF6 gas refill adjustment procedure begun in 2010 continued successfully. The objective is to identify equipment with anomalous leaks and assess the feasibility of a targeted maintenance programme. The results of the study will enable us to more precisely define a target figure for the proportion of SF6 leaks.

The programmes and initiatives in progress since 2008 for managing SF6 gas are described below:

  • procedure for monitoring leaks and reducing dispersion of the gas in the re-pressurising stage: the detection procedure involves recording the gas used and dispersed for each station (up to 2007 the measurement of leaks was given by the total quantities of SF6 purchased net of new installations);
  • compact multi-functional modules (set of different devices) which enable a 30% reduction in the quantity of SF6 necessary for insulation compared with other devices. After the positive performance test results, compact modules are considered an application standard and are installed as necessary;
  • new measurement transformers (TAs), sealed, and more reliable with maximum leaks of 0.1% per year: the plan to replace old equipment with the new transformers has been in progress since 2010.

Energy conservation in stations

Electricity is used in electricity stations to enable the equipment and remote control of the same.

We are studying initiatives to assess savings opportunities in relation to the main sources of consumption:

  • cooling power transformers;
  • external lighting;
  • conditioning and heating systems of technical rooms;
  • auxiliary command, control, and protection circuits of all equipment and machinery.

SF6 leaks: comparative data

The use of SF6 gas is a specific feature of the transmission operators sector, only figures for companies belonging to the TSO panel were considered.

The comparison between Terna and other transmission operators relative to SF6 leaks was conducted by taking the percentage of leaks compared to the total gas used as the reference.

In 2012, the average incidence of SF6 leaks for Terna was 0%; in 2011, the year for which comparative figures are available, the incidence was 0.60%.

Compared to the other transmission operators the incidence of SF6 leaks for Terna was better than average, confirming the results reported in the Sustainability Report for the last two years.  

TSO Panel: 14 figures available; average incidence of SF6 leaks: 0.85% (a decrease from the 2010 values); minimum value: 0.1%; maximum value: 3.1%; standard deviation: 0.8%.Terna comes out better than average.

The comparison with figures for 2011 is based on a larger number of companies (14 instead of 11). Considering for 2011 also, only the 11 companies considered in the previous edition, the average incidence value would be 1.1%, in line with the calculations of last year. 



* The incidence of the leaks was calculated as the percentage of leaks out of the total gas contained in the equipment.



Reduction of emissions connected with energy consumption in offices

In offices the main sources of energy consumption are connected with lighting, heating and air-conditioning, and the use of computers and printers.

In 2012 the replacement of computers and printers continued. The new models enable considerable savings in average energy consumption of 80% and a consequent reduction of carbon dioxide emissions. The reduction achieved in 2012 is in addition to that already recorded in the two years 2010-2011 (relating to replacing monitors and desktops for PCs with lower consumption) for a total of 93 fewer tonnes of CO2 emitted in the three years.

Energy efficiency

In 2011 the “Energy Consumed for Own Use Management System” project was launched. This is coordinated by the technician responsible for the conservation and rational use of energy – the Energy Manager. 

Electricity consumption for own uses was analysed starting in 2008; accuracy in data collection has therefore gradually improved, enabling a survey of electricity consumption for own uses.

The first objective achieved in 2012 was the initial energy analysis, which was carried out considering both consumption of electricity stations and consumption of the Terna Group's office buildings.

Besides the general initial energy analysis, four detailed energy analyses were carried out in relation to the following buildings:

  • Rome headquarters;
  • National Control Centre offices in Rome;
  • San Rocco al Porto Operating Group offices in Lodi;
  • Operating Area offices in Palermo.

The working group, supported by external consultants, carried out the preliminary energy audit of the buildings, focusing analysis on the main electricity supply and heating systems of the buildings. During the visits, the energy management of the buildings, and the state of efficiency of the technological plants and of the building shell were checked on site, by filling in the specific data collection forms. An inventory was also taken of all the equipment present which consumes energy..

Following the analyses, as a preliminary step, a hierarchy of actions was identified to resolve the main critical issues found, and various opportunities to improve energy efficiency were suggested.

The 2013 objective is to prepare an Energy Consumed for Own Use Management System, in line with the UNI CEI EN ISO 50001 standard and in accordance with the “Environmental Management System”. 


Reduction of emissions connected with mobility

The company's vehicle fleet – used mainly to inspect lines and for fault repair work – is not concentrated in a few places, but used over a vast area. There is therefore no problem of impact on specific areas, but rather a general polluting effect. The main actions to reduce the impact of transport on the environment consist in modernising the vehicle fleet and scrupulous maintenance.



2012 2011 2010
HYBRID 9 9 9
EURO 5 1,148 138 131
EURO 4 15 985 1,009
EURO 3 (OR LOWER) 169 219 240
TOTAL VEHICLES 1,341 1,351 1,389
(1) The table shows the vehicles of the Terna fleet which in the period in question filled up at least once as recorded on the fuel card. Only operating vehicles are considered.

Terna uses operating vehicles daily to inspect lines and reach operating plants located throughout Italy. Such inspections often require the use of all-terrain vehicles because pylons can be reached only by unpaved paths.

In 2012 there was a reduction in fuel consumption and consequently CO2 emissions fell by 355 equivalent tonnes. The lower consumption is attributable mainly to the replacement of the older models in the vehicle fleet. 1,020 models with Euro 4 or lower engines were replaced with 1,010 models with Euro 5 engines.

The replacement campaign begun at the end of 2011 envisages an offsetting project for the CO2 emissions of the new vehicles purchased, involving the creation and protection of new green areas in Rome, in the Madonnetta Park, in Madagascar and in Costa Rica.

Achievement of this objective is ensured by the collaboration between Terna, the motor manufacturers that supply the vehicles and Lifegate's Impatto Zero (Zero Impact) project.

From 2012 to 2016, the creation and protection of these wooded areas will offset the carbon dioxide emissions, quantified as 10,222,763 kg, generated by 840 vehicles in Terna's operating fleet.

The emissions were estimated from the average carbon dioxide emissions per vehicle (a figure provided by the manufacturers) for each km travelled and from the estimated number of kilometres travelled annually by the vehicles in Terna's operating fleet.

The areas involved are 14,000 sq m in Rome, 510,756 sq m in Madagascar and 2,019,848 sq m in Costa Rica.

The offsetting will cover more than 33% of the annual CO2 emissions of Terna's vehicle fleet.

During 2012, Terna confirmed the actions taken to reduce the impact of employee mobility on the environment.

Finally, in January 2013 the “Company Car Sharing” project was launched, in an experimental form for involving the operating areas of Bari and Rome. Through the use of dedicated software and a hardware device to manage the vehicles, the availability of the latter and the itineraries, kms travelled and maintenance will be monitored. The stages of booking, picking up the keys and returning the vehicle will also be automated.

The aims of the project are proper distribution of the corporate fleet around the country, route optimization (and therefore lower emissions and consumption), and greater attention to maintenance (with better performance in terms of quality, safety and respect for the environment).